Varicella pneumonia usually resolves after treatment, and occasionally miliary calcification develops on the roentgenogram of the chest years afterward. A case of varicella pneumonia is presented that followed a previously unreported course. In this case, usual interstitial pneumonitis (UIP) developed. The pneumonitis responded well clinically and radiographically to corticosteroid treatment. The role of viral pneumonia in the cause of UIP is discussed.